The objective of this proposal is to study the role of prostaglandins in the regulation of utero-placental blood flow and in hypertensive disease of pregnancy (toxemia). The principal analytic method to be employed in the radioimmunoassay of prostaglandins A, E, and F. The values of prostaglandins in peripheral plasma will be determined throughout normal pregnancy, and in a group of patients with a high incidence of toxemia. Physiological experiments will be performed on the pregnant monkey, measuring uterine blood flow, maternal blood pressure, uterine oxygen consumption, uterine vein renin activity, and prostaglandin levels. Studies will include the effect of prostaglandins, the effect of inhibitors of prostaglandin synthesis, the effect of angiotensin and angiotensin analogues (antagonists), and the response to hypoxia and ischemia. Finally, an in vitro system will be developed utilizing tissue culture of trophablastic tissue for the study of placental synthesis of prostaglandins.